It has previously been proposed to cut through the shell of a munition in order that its contents may be removed. One known method is to cut through the munition at its point of maximum girth using either a metal cutting implement or a water jet. Even when a metal cutting implement is used, the implement is normally lubricated with water and inevitably water comes into contact with the explosive material during the course of opening the shell and the water becomes contaminated.
Water that is contaminated with explosive material, referred to as pink water, cannot safely be allowed to flow into drains or into nearby rivers and itself presents a disposal problem.
DE 42 21 666 discloses a method of opening a munition that involves partially cutting through the shell of the munition using a compressed water jet to leave a very thin residual wall thickness and then applying shearing or bending forces to perform the final separation to crack open the shell of the munition. If the water jet is directed radially, the depth of the cut made by the water jet cannot readily be determined. Instead, therefore, DE 42 21 666 aims the jet tangentially, as illustrated in FIG. 1 of the patent.
It is however difficult to penetrate the wall of the munition to an accurate depth because the point of impact of the jet is distant from the tip of the nozzle. If one errs on the safe side and leaves a considerable thickness of metal behind at the end of the water jetting, then it is difficult to crack open the munition. If, on the other hand, one aims to leave a very small thickness of metal behind, then one risks, from time to time, penetrating the wall of the munition and producing pink water.